JPS60256983A - Spindle unit for reading device of disc recording medium - Google Patents

Abstract

PURPOSE:To improve the accuracy of turning by constituting a bearing placed at the device side of a disc recording medium with a ball bearing and giving a pre-load to both the bearings with the thrusting of the inner race of the other ball bearing into a turning shaft. CONSTITUTION:After the turning shaft 10, a housing 14 and the bearing 17 are assembled; the bearing 18 is pushed between the turning shaft 10 and the housing 14 toward the arrow N into press fitting. The inner race 18d of the bearing 18 is pushed axially with the turning shaft 10 as a tight fit or a transition fit, and when the side face of the outer race 18a is in contact with the inner diameter shoulder 19 of the housing 14, the pressing force is exerted in the order of the ball 18b, the outer race 18a, the housing 14, the outer race 17a, the ball 17b, and a ball orbit face 17d of the shaft 10, the inner race 18d is positioned axially to the turning shaft 10, a pre-load is given to both the bearings 17, 18 depending on the pushed position and the pre-load is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a spindle unit used in a device for reading information from a disc-shaped record carrier on which information is recorded according to a concentric or spiral track pattern. be.

2. Description of the Related Art Conventionally, spindle units used in devices for reading disk-shaped record carriers have structures shown in FIGS. 3 and 4.

The spindle unit shown in FIG.
The two ball bearings 3.4 are mounted on the rotating shaft 5 at a certain distance in the axial direction, and the shoulder on the inner circumference of the housing 2 of the bracket 1 is A spring 6 that applies a certain preload to the bearing 3.4 is provided between the bearing 4 and the bearing 4, and the bearing 3.4 is fixed to the bearing fitting surface of the bracket l and the rotating shaft 5 with the preload applied. By applying a preload using the spring 6, the occurrence of backlash caused by the presence of an internal gap in the bearing 3.4 is eliminated, and the rotation accuracy of the spindle is improved. A is a disk-shaped record carrier mounting part, and B is a motor rotor holder, each of which is fitted and fixed to the rotating shaft 5.

Incidentally, a spindle unit for a device for reading a disk-shaped record carrier is small and is required to have high-precision rotational performance, and in particular, the radial runout R of the tip of the rotating shaft on the side where the disk-shaped record carrier is attached is important in rotational performance. A thickness of 5 to 6 μm or less is required.

In recent years, the memory capacity of devices has been required to be more and more accurate, and as a result, the runout accuracy has also increased to 2 to 3 μtn.
It has become necessary to stably obtain the following: However, as shown in FIG. 3, a pair of bearings 3 supporting the rotating shaft 5
．． 4 is the outer ring 3a, 4a, the inner ring 3b, 4b, and the ball 3c.
, 4c, the precision of the fitting surfaces with respect to the housing 2 and the rotating shaft 5 inevitably varies. Therefore, it is difficult to improve the radial runout accuracy of the rotating shaft 5 as described above. In order to solve this problem, a pair of bearings 7.8 are installed as shown in FIG.
c and 8c, the outer ring 7a of the bearing 7 is loosely fitted to the inner circumferential surface of the housing, and the outer ring 8 of the bearing 8 is tightly fitted (or intermediate fit) to the pair of bearings 7.8.
A structure for applying preload without using the spring 6 as shown in FIG. 3 has been proposed. A is a disk-shaped record carrier mounting part, and B is a motor rotor holder, each of which is fitted and fixed to the rotating shaft 9.

Problems to be Solved by the Invention In the conventional structure as shown in Fig. 4, the ball raceway surface is formed directly on the rotating shaft compared to the structure shown in Fig. 3, so accuracy is easier to achieve. There is a problem.

(a) The axial spacing between both bearings 7 and 8 is narrow, making it difficult to finish the bearings and increasing the bearing manufacturing cost.

(b) In the structure in which the pair of bearings 7.8 are given preload by press-fitting the outer ring 8a of one bearing 8 into the housing 2 as described above, the force application points P1 and P2 of both bearings 7.8 are different from each other. Since it is located on the bearing side, that is, between both bearings, the axial distance between the force application points PbF2 becomes short, which is disadvantageous for reducing the radial runout R of the rotating shaft 9. In addition, Specification 1 of the present application
In , the point of force application refers to the point where the line of action that forms the contact angle of the bearing intersects the center line of the bearing.

(c) A large thrust load acts on the bearing 7 or the bearing 8 due to the magnetic attraction force of the device, but since the outer diameter of the rotating shaft 9 is determined, the ball and raceway diameters become smaller, and the bearing rating It is difficult to design a large load and the bearing life will be shortened.

(d) Runout of the rotating shaft 9 on the bearing 7 side is particularly problematic, but the outer ring of the bearing 7 and the housing must be loosely fitted, making it difficult to achieve runout accuracy of the rotating shaft 9.

Means for Solving the Problems The present invention solves the above problems by using a pair of rolling bearings arranged at an axial distance on the inner periphery of the housing. In a motor that rotatably supports a rotating shaft provided with a rotor holder, a rolling bearing located on the mounting part side of the disc-shaped record carrier is formed on an outer ring fitted to the housing, a ball, and the shaft. The rolling bearing located on the rotor holder side is a bearing with a higher load rating than the bearing and is fitted to the outer ring fitted to the housing, the balls, and the shaft. The disc-shaped ball bearing is constructed of a ball bearing having a circular inner ring, and a preload is applied to the pair of bearings by the amount of pushing in the axial direction of the inner ring of the bearing located on the rotor holder side with respect to the shaft. The solution is provided by a spindle unit for a reading device for a record carrier.

According to the configuration of the present invention, the rolling bearing located on the side where the disk-shaped record carrier is mounted, which requires rotational precision, is connected to the outer ring fitted in the housing, the balls, and the ball raceway surface formed on the shaft. The pair of bearings that rotatably support the rotating shaft rotate the inner ring of the bearing located on the opposite side (the rotor holder side of the motor) from the mounting part side of the disk-shaped record carrier. Since preload is applied by pushing the shaft in the axial direction, the force application point of each bearing is not on the other bearing side, that is, between the two bearings, but on the opposite side from the other bearing, that is, on the outside of both bearings. , the axial distance between the points of application becomes longer, and the radial deflection of the tip of the rotating shaft on the disk-shaped record carrier mounting side becomes smaller. Furthermore, since the thrust load that acts on the rotating shaft during operation of the apparatus generally acts from the rotor holder side to the record carrier mounting side, it is received by a bearing with a large rated load located on the rotor holder side of the motor.

EXAMPLE An example according to the present invention will be described. In FIG. 1, reference numeral 10 denotes a rotating shaft, and one end thereof is provided with a mounting portion 11 for a disk-shaped record carrier, and the other end is provided with a rotor holder 12 of a motor (not shown). The rotating shaft 10 is rotatably supported by a pair of ball bearings 17.18 arranged in bearing seats 15.16 formed at a constant axial distance on the inner circumference of the housing 14 of the bracket 13. . The bearing seat 15 located on the disk-shaped record carrier mounting portion ll side is formed with an inner diameter d smaller than the other bearing seat 16,
The ball bearing 17 arranged in the bearing seat 15 is attached to the housing 1
Outer ring 1 fitted to 4? a, balls 17b, a main retainer 17c, and a ball raceway surface 17d formed directly on the shaft 10. The bearing seat 16 located on the rotor holder 12 side is formed with a larger inner diameter than the bearing seat 15, and the ball bearing 18 arranged in the bearing seat 16 has an outer ring 18a fitted in the housing 14 and a ball +8b. , a main retainer 18C, and an inner ring 18d press-fitted to the shaft 10. The bearing 17 is placed in a tight fit with the housing 14 without any clearance.

The inner ring 18c of the bearing 18 is press-fitted into the rotating shaft 10 in the axial direction. This applies preload to both bearings.

That is, as shown in FIG. 2, the rotating shaft 10, the housing 14,
After assembling the bearing 17, the rotating shaft IO and the housing 14
In between, the bearing 18 is pushed in the direction of arrow N, and press-fitted. In this case, the inner ring 18d of the bearing 18 is pushed in the axial direction with the rotating shaft 10 in an interference fit or an intermediate fit, and when the side surface of the outer ring 18a contacts the inner diameter shoulder 19 of the housing 14, the pushing force is released. Ball 18b, outer ring 18a, housing 14, outer ring 17a1 ball 17b, shaft 1
0 ball orbital plane 1? d, the inner ring 18d is positioned in the axial direction with respect to the rotating shaft 10, and depending on the pushed position, a preload is applied to both bearings 17, 18, and the preload is adjusted. Also, the respective force application points P3 and P4 of both bearings 17.18 are on the other bearing side, that is, both bearings 17.1.
8, but on the opposite side from the other bearings, that is, both bearings 17.
18, and the axial distance L1 between the force application points P3 and 24 becomes longer.

On the other hand, the thrust load acting on the spindle unit is
Since it acts from the rotor holder 12 side toward the disk-shaped record carrier mounting section 11 side, it acts exclusively on the ball bearing 18 located in the rotor holder 12g1+1. Since the ball bearing 18 is a bearing with an internal force 1 larger than that of the ball bearing 17 located on the side of the disk-shaped recording carrier mounting portion 11, it has a large rated load and can therefore sufficiently receive the thrust load.

Effects of the Invention According to the configuration of the present invention, the bearing located on the mounting portion side of the disk-shaped record carrier is a ball bearing having an outer ring fitted in a housing, balls, and a ball orbit box formed on the shaft. (and is located on the other Kurogoo holder side)
Since a preload is applied to both bearings by pushing the inner ring of the bearing onto the rotating shaft, the influence on the radial run-out of the rotating shaft caused by variations in the precision of the fitting surface as in the conventional method is reduced, and the applied force is reduced. Since the distance between points becomes longer, rotation accuracy can be greatly improved. Furthermore, the thrust load acting on the spindle unit is borne by a ball bearing located on the rotor holder side and having an outer ring, an inner ring, and balls and having a large rated load, so that the life of the spindle unit can be improved. Furthermore, since the outer ring, balls, and retainer can be assembled to the rotating shaft in a single line, the assembly work of the bearing can be carried out easily and without difficulty, just like ordinary ball bearings.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory view showing the morning stand-up procedure, and FIGS. 3 and 4 are sectional views of a conventional example. IO... Rotating shaft 11... Mounting section for disk-shaped record carrier 12... Motor rotor holder 13...
Bracket 14...Housing 17, +8...
Ball bearing +7a, +8a-・Outer ring 17bS18b・
...Ball 17d...Ball raceway surface 18d...Inner ring

Claims (1)

[Claims] A pair of rolling bearings arranged at an axial interval on the inner circumference of the housing rotatably supports a rotating shaft, which has a mounting part for a disk-shaped record carrier at one end and a motor rotor boulder at the other end. In the rotor holder, the rolling bearing located on the mounting part side of the disc-shaped record carrier is composed of a ball bearing having an outer ring fitted in a housing, balls, and a ball raceway surface formed on the shaft, and The rolling bearing located on the side has a larger load rating than the bearing, and is composed of a ball bearing having an outer ring fitted in a housing, balls, and an inner ring fitted on a shaft, and the pair of bearings A spindle unit for a reading device for a disc-shaped record carrier, characterized in that a preload is applied by the amount of axial pushing of the inner ring of the bearing located on the rotor holder side with respect to the shaft.